It has heretofore been suggested that water or a mixture of water and alcohol injected into an air/fuel mixture will increase the octane rating of the mixture to produce more power without undesired detonation.
In one type of system that has heretofore been suggested, air pressure from the turbocharger is directed to a water reservoir and the pressure of the air forces the water to be injected to the intake of the engine. In another type, the pressure of the air electrically energizes a pump to pump water into the intake.
One of the problems with respect to such systems is to provide a control such that water will only be injected when the pressure of the air in the intake due to supercharging exceeds a predetermined amount.
Another problem which arises is to prevent vacuum in the intake from drawing liquid into the intake when water is not being injected.
Accordingly, among the objects of the invention are to provide a valving system which will effectively produce injection when the pressure exceeds a predetermined quantity; wherein the valve is unaffected by the liquid being injected; wherein the valve system will also prevent liquid from the reservoir from being drawn into the intake when the pressure does not exceed a predetermined amount.
In fuel injection systems, it has become common to provide an electric fuel pump in a fuel tank which delivers fuel at high pressure to the engine fuel metering system. Conventionally a fuel pressure regulator controls the pressure at the fuel nozzles by allowing a portion of the fuel to return to the fuel tank. The placement of a check valve in the return line to the tank prevents fuel from flowing out of the tank through the return line in case the return line is ruptured during an accident. It has also been proposed that a check valve be provided in the pump discharge line to prevent fuel from returning to the tank when the pump is shut off and maintain fuel pressure in the system between the check valve and the fuel pressure regulator. The check valve also functions to prevent fuel from flowing out of the fuel line in case the fuel line is ruptured during an accident. One of the problems with conventional check valves utilized in such systems is that a substantial pressure is required to open the valve thereby requiring a pump having a greater capacity than is normally required in the fuel metering system. Such a high pressure drop across the conventional check valve may also cause foaming of the fuel under high temperature conditions.
Accordingly among the further objectives of the present invention are to provide a valve which requires minimal pressure to open and prevents reverse flow when the pressure is present in the fuel and the pump is not operating.